With the advancement of medical treatments and technologies, bacterial infection has become a growing concern in the course of patient care.[1] In the United States, approximately 2 million hospital patients develop a hospital-acquired infection each year.[1] Due to illness, organ trans-plantation, or specific disease treatments, many patients possess a depressed immune system that renders the individual more susceptible to infection. [2] Further, prosthetic materials such as stents, mesh grafts, and catheters can provide additional microenvironments for bacterial growth.[3] Antibiotic-resistant bacteria strains increase the severity of illness, length of hospital stay and mortality from infection.[4] Consequently, new agents and techniques to prevent, diagnose, and treat bacterial infection are needed.
Typically an accurate diagnosis of bacterial infection is derived from cultures of samples obtained from the site of suspected infection. Other clinical methods to identify infection include monitoring of body temperature, white blood cell count, erythrocyte sedimentation rate and cytokine reactions—none of which are a specific response to infection.[5] Consequently, these tests cannot differentiate between bacterial infection and sterile inflammation, and are prone to false positive results due to contamination.[6]
As a result, there is a need to develop molecular imaging probes that can specifically identify bacterial infection, monitor therapeutic response, and ultimately guide clinical decisions. Additionally, bacteria-specific contrast agents could aid in the study of infection pathology. Bacteria-targeted imaging probes would allow for in vivo monitoring of both infection progression and antibiotic effectiveness (e.g., in animal models). This could lead to the development of new antibiotics capable of targeting bacterial strains that have developed resistance to current medications.